I suggest two important aspects to our response: wisdom and authority.
Wisdom is finding ways to affirm what is affirmable and to question what is questionable. At all times wisdom is the refusal to accept false alternatives, poor arguments, misconceptions and the like. Authority is engaging with the differing but connected authorities involved in questions concerning the dignity of human beings. Parliament has the authority to propose, consider, debate, revise and finally resolve legislation. Christians seek generally to abide by legitimate authority (and sometimes have an appalling track record of not opposing illegitimate authority) yet always live under the authority of God as Lord of all lords and King of all kings.
I guess this may not be the only post on this debate over the next weeks and months so the following few thoughts are not intended to constitute a comprehensive reflection on the matters at hand.
Affirming what is affirmable: whatever else is going on in the push for gay 'marriage', people in same sex partnership are asking for equality of treatment around matters such as property, inheritance, next of kin status which (as far as I can see) can be affirmed by Christians.
Questioning what is questionable: I suggest there are some hidden consequences in the push for gay 'marriage' in terms (as in the linked report above) of 'equality' which need bringing to the light for debate, for questioning because there are some questionable matters here.
One question concerns whether, post legalising gay 'marriage', any discrimination between marriages (i.e. straight/gay) will be possible? Discrimination is a loaded term here but let's not euphemise it away with other words such as 'distinctive/distinguishing'. In public debate no one (I suspect) wants to raise such questions as it is politically incorrect to talk of discrimination, but might (to give an obvious example here) churches wish to be able to discriminate? For instance to be able to ask of the person applying to be the minister of a church whether 'married' in their CV means married to a person of the opposite or same gender?
Another question concerns adoption of children. Now I get it that a blanket ban on same sex couples adopting children doesn't work in various ways (e.g. it might deprive an unwanted-by-any-other-couple child of a loving home, it would forbid a reasonable proposal that a once married-now-widowed man who marries another man from having his own natural children adopted by his new partner). I also get it that married couples have the right to adopt. But is there not also a right of children to have the opportunity to be raised by a dad and a mum? To recognise this right is not necessarily to trump other rights, but should it be kept in sight rather than lost in rhetoric about gay parents being just as good as straight parents etc? All things being equal about a prospective adoption is it unreasonable to suggest that the right to be raised by a mum and a dad outweighs the rights of two men or two women to adopt?
What about authority? Last night I voted against legalising gay 'marriage'. I am not a politician but I am on Facebook! Why vote against? Because I am not convinced that God has authorised humanity to change the definition of marriage in respect of the genders involved. Parliament has authority but in Christian understanding it is an authority derived from God's authority. To that higher authority I look in vain for the disclosure or revelation of a new understanding of marriage.
For Anglicans this talk of authority may or may not wash. Already on Facebook I have seen one colleague make a comment which effectively translates as, the church needs to catch up with what Parliament is likely to decide. Fancy that! But what is unsurprising about such a comment is that it involves a muddled sense of what constitutes authority within a shared Anglican understanding and appreciation of authority. Appropriately we now have Michael Poon's latest Anglican essay available via Fulcrum. Entitled 'A Vision for the Fellowship of Anglican Churches', Michael touches on authority in these words,
"Most Anglican undertakings lack ecclesial consistency, especially those at international levels. Discussion and decision in international meetings do not carry any weight at local levels; ecclesiastical policies vary with change of leadership; Communion-level undertakings are mainly fund-dependent and therefore short-term by nature. The ecclesial deficit that the Windsor Continuation Group identifies in fact is endemic beyond the Communion structures, to the 'five marks of mission,' the rationale of qualification of Communion membership, and the 'autonomous province' concept. To Christopher Dawson (and John Henry Newman), this deficit goes to the heart of the Church of England: it lacks a proper authority structure. (See Adam Schwartz's discussion on Christopher Dawson in The Third Spring: G.K. Chesterton, Graham Greene, Christopher Dawson, and David Jones, 202-285.)
Shorn of a coherent intellectual and theological account, global Anglicanism is therefore bound to collapse, and is at risk of splintering into tribalism. Remarkably, over the past decades the creative ecclesiological reflection in ecumenical conversation had not fed into the Communion-structure-building exercises." [my bold]But the fact that broadly speaking Anglicanism suffers from a malaise about authority does not mean, dear reader, that you and I need be afflicted by it. Anglicanism suffers that malaise where it refuses to engage with what authority has meant for Anglicanism, both in the sense of the distinctive birth of modern Anglicanism (i.e. the Reformation) and in the sense of 'what many Anglicans have subscribed to'. The authority of which I speak is precisely the authority of Scripture, informed by Tradition and influenced, but not negated by Reason.
Onwards and upwards to the sunny uplit lands of being Christian (and Anglican) in this strange new world of the 21st century!